This invention relates generally to packaging, particularly of foodstuffs, and more particularly to a vacuum packaging method and an apparatus in which, through the use of a packaging bag of a heat-shrinkable plastic film, vacuum packages containing a vacuum packaged foodstuff, particularly a livestock meat for food, are formed.
In a representative vacuum packaging method of similar character known and generally practiced heretofore, packages of hams, sausages, and like meat products are formed. This known method includes the package forming steps of filling a hollow cylindrical heat-shrinkable plastic film with the content to be packaged, constricting and closing the two open ends of the cylindrical film with clips, and thereafter causing the film to shrink with hot water. While this packaging expedient, strictly speaking, cannot be considered to evacuate fully the interior of the package, the package in this case is kept in the hot water for a time necessary for sterilization, and, therefore, no particular problem should arise thereafter.
On one hand, vacuum packages of raw meats of livestock packaged with the above mentioned packaging material formed into bags by a procedure comprising filling each bag through an open end thereof with the raw meat, inserting an evacuation nozzle into the opening of the bag and evacuating the bag, constricting and closing the opening with a clip, and causing the bag to shrink have been placed on the U.S. market and have been disclosed in the local trade journals.
In the case where the commodity packaged is raw meat, however, it is not possible to immerse each package in hot water for a period of time amply sufficient for thorough sterilization. For this reason, there is a high probability of decomposition and spoilage being caused by the nature of the closure of each bag by means of a clip, as described hereinafter. This packaging state is undesirable for food distribution and marketing.
Another difficulty encountered in vacuum packaging of the instant character is that the foodstuffs, particularly raw meats, are not uniform in size and shape. Still another difficulty is that the surfaces of meats, both raw and processed (e.g., bacon), are slightly damp and, moreover, tend to be tacky. These difficulties all cause difficulty in attaining full evacuation of the packaging bags and full suppression of generation of gases conducive to decomposition, and have required considerable preconditioning.
Accordingly, an efficient method by which it is possible to obtain full evacuation of each bag without the accompaniment of the above mention problems is urgently needed.